The present invention is generally directed to electronic devices that produce or encounter predictable and/or internally generated signals, and in particular, to an improved method of more accurately compensating for such predictable and/or internally generated signals. Specifically, by way of example, the present invention is directed to electronic devices that include a “compass mode” in which the device can receive and display directional headings. More specifically, the present invention is directed to a method of more accurately determining directional headings in such an electronic device such as a timepiece, and a watch in particular, that includes one or more stepper motors, such as a Lavet stepping motor, which have the capability to produce magnetic fields which, if not accurately compensated for while the electronic device is in the “compass mode,” can significant affect the directional heading readings.
Typically, “all digital” watches do not include any internally generated electromagnetic (i.e. electric and/or magnetic) fields. For example, such watches typically do not include any stepper motors, and use only LCD displays for the display of all information, including the “time of day” (“TOD”). More specifically, those “all digital” watches that do include a compass mode can obtain fairly accurate directional heading readings because there is typically no internally changing magnetic fields, such as those created by the rotors of such stepper motor being in different orientations, to interfere with such readings.
However, not all consumers prefer such “all digital” watches, and instead, prefer watches with some amount of analog display functionality, i.e. watches which tell time or other information using hands. In watches that drive such hands by the use of stepper motors, attention needs to be made to the magnetic fields caused by the rotor which may adversely affect the directional heading readings, since practically speaking, the duration of the time period during which directional heading readings are obtained will include the period where the rotor would typically passes through both orientations (e.g. 180° apart).
Therefore, in watches that are “all analog” or which may include functions of both an analog watch and digital watch, such as the “combo” watch, an example of which is described in U.S. Pat. No. 5,691,962 the subject matter of which is incorporated by reference as if fully set forth herein, it is desirable to take into account the orientation of the rotor when taking directional heading readings.
In the marketplace, there is at least one watch that includes both hands for telling time (i.e. an analog watch) and a compass mode, such watch being marketed and sold under the brand name Tissot T-Touch. Contrary to the construction provided in the instant application, the Tissot T-Touch uses the hour and minute hand to indicate the direction. That is, during the normal time telling mode, the Tissot T-Touch tells time in the traditional manner (i.e. with its hour and minute hands). However, upon the activation of the compass mode, the hour and minute hand become aligned to act as a compass direction indicator (i.e. pointing North). Whether or not the internal methodology in the Tissot T-Touch takes into account the possibility of changing magnetic fields created in the watch during directional heading readings (i.e. it is noted that the rotor must be rotating to permit the hands to continually rotate) so as to provide for increased accuracy in its directional heading readings, it will become quite apparent that the present invention is directed to a starkly different methodology.
Thus, it has been recognized that advances in the methodology to compensate for predictable and/or internally generated signals in electronic devices are desired. Specifically, by way of example, it is desired to provide an improved methodology for compensating for the magnetic fields created by the one or more rotors of a stepper motor in an electronic device. In particular, it is desirable to provide an improved method of more accurately determining directional headings in an electronic device that includes a sensor for taking such readings, such as a timepiece, and a watch in particular, that includes one or more stepper motors. The present invention overcomes the perceived deficiencies in the prior art as well as achieves the foregoing and below mentioned objectives.